System and method for electrical power generation utilizing vehicle traffic on roadways

ABSTRACT

The present invention relates to methods and systems for power generation including a method and system for electrical power generation by utilizing forces due to vehicle weights from traffic on roadways. An embodiment of the invention uses multiple compressible hydraulic cylinders of different types, the cylinders used being dynamically selected responsive to the various weights of the vehicles presenting.

RELATED APPLICATION

This application is a continuation of co-pending U.S. patent applicationSer. No. 10/428,998 filed May 2, 2003 which claims priority to U.S.provision patent application No. 60/380,056 filed May 6, 2002 forinventor Terry Douglas Kenney also known as Terry Kenney.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to methods and systems for powergeneration. More particularly, the present invention is a method andsystem for power generation including electrical power generation suchas by utilizing vehicle traffic on roadways.

BACKGROUND AND RELATED ART

Energy sources useful for the generation of electricity include wind,water, solar, nuclear and steam energy and various methods and systemshave been developed for harnessing such energy to generate electricity,typically by performing useful work to drive an electric generator.

With the continuing need for energy consumption efficiency andconservation, many efforts have been made to exploit previously unusedenergy sources. Many methods and systems have been proposed for theharnessing of existing forces or mechanical work to generate electricalpower. In particular, several systems and methods have been developed touse the energy and downward force of the wheels of vehicles as they movealong a roadway surface.

The systems can be categorized generally as mechanical systems, aircompression systems and hydraulic systems.

Mechanical Systems.

Mechanical systems for generating electric power from the downward forceof vehicles passing over a roadway typically involve gear mechanisms andother moving parts and are prone to wear and tear from the stress offorced downward movement in response to vehicles and forced upwardmovement when being reset. One example is U.S. Pat. No. 4,238,687 toMartinez discloses a system for generating electric power from thepassage of motor vehicles over a roadway using turbines that are drivenby the downward rotational movement of arc-shaped arms connected torocker plates installed on a road surface when such rocker plates areforced down by vehicles passing over them.

Air Compression Systems.

Air compression systems typically involve an air compression pistonbeing driven by an actuator of some sort that translates the downwardforce of a vehicle passing over a roadway in which the actuator isinstalled. For example, U.S. Pat. No. 4,173,431 to Smith discloses aroad vehicle-actuated air compressor and system for using compressed airto operate an electrical generator to generate electricity. The roadvehicle-actuated compressor includes an actuator that is pushed downwardby the weight of vehicle tires passing over it, driving a reciprocatingpiston in a cylinder, compressing the air in the cylinder. An electricgenerator is driven by compressed air from the cylinder. Another exampleis U.S. Pat. No. 5,634,774 to Angel et al. which discloses a roadvehicle actuated air compressor which utilizes flaps mounted in pairs ina road or pedestrian walkway surface. When traffic moves over the flaps,the flaps move downward to activate a piston which compresses air. Thecompressed air is stored and used as needed to generate electricity. Aircompression systems, while generally somewhat more durable thanmechanical systems, are not efficient in maximizing the amount of energytranslated from the downward forces of moving vehicles to drive anelectrical generator, due to friction and other losses.

Hydraulic Systems.

Several systems utilize hydraulic pumps to absorb the downward force ofvehicles passing over a roadway and translate same into useful work,such as to drive an electric generator. For example, U.S. Pat. No.4,004,422 to Le Van discloses a method and apparatus for producinguseful work utilizing the weight of moving traffic by incorporating in aroadway or traffic-way a readily deformable chamber which is filled witha fluid, arranged so that the weight of the vehicle is passing over itcauses displacement of the fluid contained therein. The energy of thedisplaced fluid in turn is translated into mechanical or electricenergy. U.S. Pat. No. 4,130,064 to Bridwell discloses a system forutilizing the weight and momentum of moving vehicles to produce usableenergy comprising a fluid displacement pump positioned either under amoveable plate in a roadway or between the rail in a railbed in arailway which compresses hydraulic fluid as the vehicle passes over, alow pressure line for supplying fluid to the pump chamber, a highpressure outlet line communicating with the chamber and connected to amanifold which is supplied with high pressure fluid from a number ofother similar pumps and which directs the fluid to an energy conversiondevice such as a fluid motor and electric generator. The inventionteaches use of a dual-stroke pump actuated depending on the weight ofthe passing vehicles. The dual-stroke pump allows greater volumes ofhydraulic fluid to be pressurized depending on the weight of the passingvehicle.

Similarly, U.S. Pat. No. 4,211,078 to Bass is directed to a power sourcecomprising a cylinder arranged to pump hydraulic fluid into a pressureaccumulator. The stored hydraulic fluid operates a hydraulic motor todrive an alternator to generate electric power. The cylinder can be asingle acting cylinder having a piston rod depressed by the weight ofpassing traffic on a highway. The system uses an accumulator and ahydraulic motor which drives an alternator to generate electric power.U.S. Pat. No. 4,409,489 to Hayes discloses an apparatus whichpressurizes fluid and causes it to flow by capturing energy dissipatedby moving vehicles, comprising a network of collapsible bodiescontaining hydraulic fluid attached to a turbine generator system. Thecollapsible bodies are resilient tubes, preferably three-part structuresmade of elastic inner tubes with projections and outer sections ofsemi-rigid hose. The claimed improvement is in the use of a network ofnumerous collapsible bodies to capture more weight from passingvehicles.

More recent efforts include U.S. Pat. No. 6,172,426 to Galich disclosesan energy platform system for generating electrical energy from theweight of a moving vehicle comprising a fluid bed containing a volume offluid which is compressible by the weight of a moving vehicle drivenover it. Fluid forced from within the bladder as a result of suchcompression passes through a circulation system where the moving fluidis used to drive a generator. The circulation assembly comprises anaccumulator in fluid communication with the bladder, which receives theforced fluid and releases it at a specified pressure level. A hydraulicpump and reservoir are also used. The electrical generator is a lineargenerator, comprising an elongate cylinder having a hollow interior. Theexterior of the cylinder has a coil around it. A rod is inserted withinthe cylinder and has a magnet slidably coupled to it. As the rod in thecylinder is moved by the hydraulic fluid, the magnet moves as well,causing an electrical current within the coil. U.S. Pat. No. 6,204,568to Runner discloses a system for converting mechanical motion ofvehicles into electrical energy, comprising a plurality of motionconverter assemblies each including a rod which remains in communicationwith a vertical motion delivery mechanism through a gearing mechanismfor rotating the rod in response to vehicle traffic passing over thesystem, a plurality of fluid pumps each connected to the rotating rod togenerate pressurized fluid which in turn drives a turbine generator. Themotion converter assemblies have a rectangular base and sides forming abox an are inserted in the road surface. The motion converter assembliesalso have a pair of rectangular top plates that are pivotally connectedat one end to one side of the motion connection assembly base, withsprings urging the plates upward. The top plate has a vertical platepivotally connected to its under side which has teeth to engage a gear.When a vehicle passes over the top plate of a motion converter assembly,the vertical plate is driven downward and engages the gear, whichrotates and drives the fluid pumps.

These previously described systems, while in principle capablegenerating electrical power from the downward force of vehicles as theypass over a roadway, are inefficient in their ability to maximize theelectrical power generated from each passing vehicle. Vehicles havevarying weights; the downward force of a semi-truck is obviouslyconsiderably more than that of a compact car. Prior systems do noteffectively harness the full force of each vehicle. Additionally,because vehicle traffic is typically irregular, there is an increasedneed in such a system to maximize the transfer of energy from eachvehicle and store energy to provide a steady supply of electric power.An embodiment of the present invention is a system and method forgenerating power, such as electrical power, from downward vehicle forceson a roadway that effectively harnesses the energy of vehicles ofvarying weights. Embodiments of the present invention may overcome theshortcomings of prior efforts by employing multiple hydraulic cylindersof different load bearing and hydraulic fluid compression capacitiesthat are selectively activated by a sensor system depending on vehicleweight in a novel combination and configuration with a road plate overwhich vehicles pass. Embodiments of the present invention caneffectively harness the downward force of both moving and stationaryvehicles.

SUMMARY OF THE INVENTION

The invention includes methods and apparatuses for power generationsystems. According to an aspect of the invention a power generationsystem comprises a hydraulic accumulator, a hydraulic reservoir;electric hydraulic cylinders having various weight-handling capacitiesand a vehicle weight sensor.

According to a further aspect of the invention, a method for powergeneration comprises providing electric hydraulic cylinders, sensing aweight, selecting cylinders and directing hydraulic fluid to them andusing the weight to force hydraulic fluid.

According to a still further aspect of the invention a power generationsystem is disclosed. It may comprise a hydraulic fluid accumulator and atwo level road plate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram depicting certain components of an embodiment of thesystem of the present invention in a preferred embodiment.

FIG. 2 is a diagram depicting additional detail regarding the layout ofthe components of an embodiment of the system of the present inventionin a preferred embodiment.

FIG. 3 is a top plan view of certain elements of the road platecomponent of an embodiment of the system of the present invention in apreferred embodiment.

FIG. 4 is a top perspective view of certain elements of the road platecomponent of an embodiment of the system of the present invention in apreferred embodiment.

FIG. 5 depicts a side perspective view of certain elements of the roadplate component of an embodiment of the system of the present inventionin a preferred embodiment.

FIG. 6 depicts a side cross-sectional view of a step assembly of theroad plate component of an embodiment of the present invention in apreferred embodiment.

FIG. 7 depicts a side cross-sectional view of the road plate componentof the system of an embodiment of the present invention in a preferredembodiment utilizing a two-level road plate configuration.

FIG. 8 depicts a side perspective view of an electric hydraulic cylinderof the road plate 25 component of an embodiment of the system of thepresent invention in a preferred embodiment.

FIG. 9 depicts a cross-sectional view of an electric hydraulic cylinderof the road plate component of an embodiment of the system of thepresent invention in a preferred embodiment.

FIG. 10 is a diagram of the hydraulic system of an embodiment of thepresent invention in a preferred embodiment.

FIG. 11 depicts a side perspective view of the bottom level road plateassembly used in a preferred embodiment of the invention utilizing atwo-level road plate configuration.

FIG. 12 depicts a side perspective view of the top level road plateassembly used in a preferred embodiment of the invention utilizing atwo-level road plate configuration.

FIG. 13 depicts a side and top perspective view of the top level roadplate weldment used 10 in a preferred embodiment of the inventionutilizing a two-level road plate configuration.

FIG. 14 depicts a side and top perspective view of the bottom level roadplate weldment used in a preferred embodiment of the invention utilizinga two-level road plate configuration.

FIG. 15 depicts the road plate action when a vehicle passes over it.

FIG. 16 is a block diagram that shows the relationship between somecomponents of an embodiment of the invention.

FIG. 17 is a flow diagram for one or more embodiment of the invention.

For simplicity in description, identical components are labeled byidentical numerals in this document.

DETAILED DESCRIPTION

In the following description, for purposes of clarity and conciseness ofthe description, not all of the numerous components shown in theschematic are described. The numerous components are shown in thedrawings to provide a person of ordinary skill in the art a thoroughenabling disclosure of the present invention. The operation of many ofthe components would be understood and apparent to one skilled in theart.

An embodiment of the present invention provides a system and method forelectrical power generation utilizing vehicle traffic on roadways. Thesystem of the present invention, in a preferred embodiment may compriseseveral main components such as a road plate comprising one or moresteps and/or arms having electric hydraulic cylinders disposed withinthem that are actuated when vehicles pass over the road plate and avehicle weight sensor system that activates specific electric hydrauliccylinders of varying weight handling capacities depending on the vehicleweight sensed by such sensing system; a power generation system that mayinclude a self-contained hydraulic system; and may include an electricalpower transmission system.

Road Plate

Referring to FIG. 1, which is a general block diagram of the overallsystem, the road plate component 100 is designed to capture the weightof vehicles passing over it. Multiple road plate components can be used.In one embodiment of the system as depicted in FIG. 7, a two-level roadplate configuration is utilized, in which the lower level has highercompression capacity hydraulic cylinders that are activated depending onincreased vehicle weight, with the upper level handling lower weightvehicles. FIGS. 11-14 depict the main top and bottom level road plateassembly components, showing the weldment assemblies with the levelframes, springs, mounts, and hydraulic cylinders. Multiple level roadplate configurations can be used in alternate embodiments of theinvention.

Referring to FIG. 4, in a preferred embodiment, the road plate componentcomprises five main subcomponents: a front step weldment 18, a rear stepweldment 20, a base plate weldment 16, aligned with the front stepweldment and the rear step weldment and disposed underneath each,forming the base therefor, one or more hydraulic steps or arms, eachhaving one or more electric hydraulic cylinders 10, and as depicted inFIG. 8 a vehicle weight sensor system that activates specific electrichydraulic cylinders of varying weight handling capacities depending uponthe vehicle weight sensed by such sensing system. In a preferredembodiment, one or more piezo-electric traffic sensors may be utilized.Other known sensing mechanisms and systems can be utilized as well. Thefront step weldment 18 and the rear step weldment 20 may moveindependently of each other. Although the number of hydraulic cylinderscan vary, each weldment is preferably attached to four electrichydraulic cylinders, with one at each corner. The base plate componentsare preferably constructed from welded aluminum or steel, although otherrigid and durable materials such as plastics, fiberglass and othermetals and composite materials can be utilized. Additionally, asdepicted in FIG. 5, a guide tube 3 fits over another tube welded to thebase plate 16. This guide tube 3 allows each front step weldment andrear step weldment to move vertically up and down, but not move side toside or front to rear. When a vehicle drives on top of a step, thecylinders are forced to retract. Coil springs are used in a preferredembodiment to force the front step weldment and the rear step weldmentupward to their extended position after being forced down by passingvehicles. Shocks, struts and hydraulic return systems can also be usedto perform this function.

Referring to FIG. 3, the hydraulic arms 130 and 140 used in combinationwith steps as 5 described above in a preferred embodiment in the roadplate component, resemble railroad track rails in appearance, but have abase plate having a bottom and side walls and a top plate having a topand side walls that are configured to fit over the side walls of thebase plate. Within the chamber formed in the space within the base plateand top plate are disposed one or more electric hydraulic cylinderswhich are connected via hydraulic fluid discharge lines to one or morehydraulic fluid accumulators forming part of the power generation systemof the present invention described below. The electric hydrauliccylinders in the arms, as well as those in the steps, can beinterconnected via hydraulic fluid lines in parallel, in series, or inother known configurations. Coil springs or other means as describedabove can be used in the arms to return the top plate to its extendedposition after being forced down by passing vehicles.

The layout of the hydraulic arms on the roadway surface may be a factorin the improved efficiency provided by the present invention. Asdepicted in FIG. 3, in a preferred embodiment, the arms 130 and 140 areconfigured in a “zigzag” pattern in a direction parallel to oncomingtraffic, and are placed before the steps so that vehicle traffic passesover the arms before passing the steps. The layout and spacing of theelectric hydraulic cylinders 150, 151, 170, 171, 180 and 181 within thearms can vary as desired for the specific application, but preferablythe electric hydraulic cylinders may be laid out within the “zigzag”pattern of the arms such that two or more electric hydraulic cylindersare aligned in parallel with vehicle traffic, at or near the roadsurface where vehicle tires typically make contact.

Referring to FIG. 8, the electric hydraulic cylinders themselves arepreferably made of 25 metal or other materials known to be suitable forsuch applications, and have a piston slidably disposed within innercylinder wall. FIG. 9 is a technical drawing of an example of one suchsupply line and a hydraulic fluid discharge line, as well as positiveand negative electrical wires or cables connecting the electrichydraulic cylinder to the solenoid of the sensing system. Hydraulicfluid is supplied to fill the cylinder from the hydraulic fluidreservoir 700 of the power generation system component. The electrichydraulic cylinders are activated by the vehicle weight sensing systembased on the vehicle weight sensed and when the sensed vehicle passesover the arms or steps within which the particular activated cylinder isdisposed, the cylinder piston is forced downward in the cylinder forcinghydraulic fluid through the hydraulic fluid discharge line to thedesignated accumulator of the power generation system component.

As can be recognized, the number of electric hydraulic cylinders used,as well as their size and force handling capacity can vary and can beconfigured to meet the needs of the desired application. For example, aplurality of electric hydraulic cylinders can be interconnected to asingle circulation assembly or manifold or can be connected torespective individual circulation assemblies or manifolds for redundancyof operation.

Vehicle Weight Sensing.

In one embodiment which uses piezoelectric sensors for vehicle weightsensing, the piezoelectric sensors may be installed as part of the roadplate component in the road surface ahead of the hydraulic arms, and areused to sense vehicle weight and signal specific electric hydrauliccylinders to capture the full weight of, and maximize the powergenerated from, the passage of each vehicle over the road platecomponent.

Referring to FIG. 2, vehicles traveling on the roadway where theimproved invention is installed first cross piezoelectric sensors,preferably approximately fifteen to twenty feet ahead of where thehydraulic arms are located. If a vehicle exceeds the pre-set weight, asignal will be sent by the sensor to activate specific electrichydraulic cylinders capable of capturing increased vehicle weight formaximum power generation. The signals may be controlled using anelectric solenoid switch. The piezoelectric sensors are installeddirectly into the road in a manner that allows them to conform to theprofile of the road. The sensors may also be used for counting vehiclesin order to calculate maintenance and other performance data.Piezo-electric sensing systems such as the Roadtrax® Piezo-electrictraffic sensors manufactured by Measurement Specialties, Inc. aresuitable in embodiments of the system of the present invention, althoughother known traffic sensing systems can be used. Such sensors are only1/16″ thick and ¼″ wide, and can be installed with only ¾″ wide by314″-1″ deep slots in the road surface, minimizing the damage done tothe road, speeding up installation and reducing the amount of groutneeded for installation. The sensor can provide high signal output andgood dynamic range. The flat construction of the sensor providesimproved road noise rejection.

Piezoelectric polymer film provides high sensitivity, broad bandwidthand wide dynamic range. A cable form of sensor is preferably used,comprising piezopolymer extruded directly onto a stranded core wire,with conventional braid and jacket similar in appearance to a smallcoaxial signal cable. One of the inherent advantages of piezo cable overother forms of sensors is the ability of the cable to detect impacts orvibration ranging from very weak pressure signals caused by ground-bornevibration, through to impacts from heavy vehicle axles at high speed.The present invention utilizes this increased sensing capacity tomaximize the energy harnessed from each passing vehicle.

As vehicles move across the arms containing hydraulic cylinders, theweight of the vehicle is captured by the electric hydraulic cylinders,which then feed pressurized fluid into the power generation systemcomponent of the present invention. As the vehicles move forward throughthe road plate component, the rear step weldment adjusts based on thepiezoelectric weight sensor input to engage additional cylinders. Thevehicles pass over the arms activating the hydraulic cylinders below andthe downward force of the vehicle's weight forces hydraulic fluid to bepumped to drive the power generation system component. The piezoelectricsensors send a signal to a solenoid switch to direct the operation of aflow director to direct the flow of hydraulic fluid to the appropriatehydraulic cylinders based on the weight of vehicle. Various flowdirector manifold components available on the market can be utilized inthe present invention. In one embodiment, an integrated hydraulicmanifold flow divider manufactured by Moog, Inc. is used.

Power Generation System

FIG. 16 is a block diagram that shows the relationship between somecomponents of an embodiment of the invention. FIG. 17 is a flow diagramfor one or more embodiment of the invention.

Referring to FIG. 1, the power generation system component, in apreferred embodiment, comprises one or more accumulators 300 preferablywith one acting as the main accumulator attached to the system tocapture average weight of all traffic, and another accumulator connectedto the hydraulic cylinders driven by the weight of more heavy vehicles;a hydraulic motor 600, and an electricity generator 800 driven by thehydraulic motor 600. The accumulators feed into one motor system. Apressure control/release 400 and regulator 500 control accumulation andrelease of hydraulic pressure. The accumulators pre-pressurized to a setlimit, store the energy until maximum capacity is reached at which timethey discharge, releasing 3000 or more pounds per square inch, turningthe hydraulic motor 600. The hydraulic motor 600 operates based on theamount of pressure released and subsequent free flow, which turns agenerator 800 to produce electricity. The accumulators are connected tothe base plate's electric hydraulic cylinders by hydraulic fluid supplylines and connections. Each different weight of vehicle has thepotential to generate a different amount of pressure in the hydrauliccylinders. This is captured and turned into a uniform pressure chargingthe accumulators. To accomplish this, a gear type flow divider ispreferably used to intensify the pressure when a light vehicle passesover the road plate component. For example: a light vehicle passes overthe mechanism and generates 500 PSI of pressure and 3.14 cu. inches ofvolume. The flow divider will reduce the flow to about 0.785 cu. inchesbut increase the pressure to 2000 PSI. Sequence valves sense thepressure generated by the vehicle and control the flow from each sectionof the flow divider accordingly. The accumulators start with a setprecharge and increase in pressure to a desired setting. The kickdownvalve 400 at the accumulator outlet opens when the desired pressurelevel is reached and spins the hydraulic motor 600 which turns thegenerator 800. The hydraulic motor also supplies hydraulic fluid to ahydraulic fluid reservoir 700 which in turn provides a supply ofhydraulic fluid to re-fill the electric hydraulic cylinders.

Electrical Power Transmission System

The electrical power transmission system component, in a preferredembodiment, comprises a switch gear mechanism 900 and an electricalconduit junction communications with an electrical utility supply grid1000. The generator 500 is connected by known electrical connectionmeans through a switching gear 900 to an existing electrical facilityjunction box 1100 or electrical utility grid 1000 to supply electricity.To further enhance the generation of electricity, a solar panel can beadded to the power plant component.

The solar panel feature is included as part of FIG. 2. The solar panelpowers a DC motor to operate a hydraulic pump that feeds fluid into theaccumulator. This reduces the volume of traffic required to cross thesystem to generate electricity and increases the efficiency of theoverall unit. Additionally, the solar panel can be used to power asecurity alarm on the power plant/generation house.

The overall system is a closed modular designed unit. The road plate canbe divided into sections. The system can be pre-assembled on a 10′×8′skid which would include the accumulator, hydraulic motor and generator.The road plate can be installed in sections with minimal cuts to theroadway and conforms to profile of the road.

Methods for Generating Electricity Using System.

The method of the present invention, in a preferred embodiment, maycomprise the steps of driving a vehicle over a road plate having one ormore steps or arms with electric hydraulic cylinders having varyingweight handling capacities disposed within them that are actuated when avehicle travels over the road plate, and having a vehicle weight sensorsystem that activates one or more of the specific electrical hydrauliccylinders depending on the vehicle weight sensed by the sensor system;transferring the hydraulic pressure created by the electric hydrauliccylinders when a vehicle travels over the road plate from the electrichydraulic cylinders to a power generation system comprising one or moreaccumulators connected by hydraulic fluid supply lines to the electrichydraulic cylinders to receive and store pressurized hydraulic fluidsupplied by the electric hydraulic cylinders, a hydraulic motor drivenby pressurized hydraulic fluid supplied by the accumulators and anelectricity generator driven by the hydraulic motor to generateelectricity.

The present invention can be designed to capture as much energy aspossible from each vehicle, including light passenger vehicles to busesand heavy trucks. Preferred locations for installation may includeparking garages, shopping center or recreation/amusement park parkinglots and similar locations with relatively steady vehicle traffic.

Vehicles on the road have widely varying weights and because the frontaxle weights versus rear axle weights of vehicles differ substantially,the present invention can capture the energy supplied at many differentpressures. The use of dual accumulators each receiving hydraulic fluidfrom cylinders of different weight handling capacities as activated bythe vehicle weight sensing system allow for greater energy harnessing.If a single accumulator is used, a substantial fraction (more than half)of the energy potential of larger vehicles is lost because theaccumulator would have to be operated at a low pressure in order tostore the energy from smaller vehicles. The present invention providesfurther efficiency by use of a gear type flow divider to decrease theflow rate but increase the pressure delivered by the lighter vehicles.In sample calculations, overall efficiency of the accumulators ingathering the energy is estimated at approximately 70%, based on aweighted average of the front and rear axle efficiencies of thedifferent sized vehicles.

While the present invention has been shown and described herein in whatis considered to be a preferred embodiment thereof, illustrating theresults and advantages over the prior art obtained through the presentinvention, the invention is not limited to the specific embodimentsdescribed above. Thus, the forms of the invention shown and describedherein are to be taken as illustrative and other embodiments may beselected without departing from the spirit and scope of the presentinvention.

The embodiments described with reference to the Figures are exemplaryonly, and many other comparable configurations will be apparent to oneof ordinary skill in the art.

Embodiments of the invention as described herein have significantadvantages over previously developed implementations. As will beapparent to one of ordinary skill in the art, other similar apparatusarrangements are possible within the general scope of the invention. Theembodiments described above are intended to be exemplary rather thanlimiting and the bounds of the invention should be determined from theclaims.

1. A power generation system comprising: a hydraulic accumulator coupledto a hydraulic motor; a hydraulic reservoir; at least one electrichydraulic cylinder having a lower weight-handling capacity coupled tothe accumulator and further coupled to the hydraulic reservoir; at leastone electric hydraulic cylinder having a higher weight-handling capacitycoupled to the accumulator and further coupled to the hydraulicreservoir; at least one flow director coupled to the at least oneelectric hydraulic cylinder having the higher weight-handling capacity;and a vehicle weight sensor coupled to the flow director.
 2. The systemof claim 1 wherein: the vehicle weight sensor comprises a solenoid. 3.The system of claim 1 wherein: the hydraulic motor is coupled to anelectric power generator.
 4. The system of claim 1 wherein: the vehicleweight sensor is operable to control the flow director in response to asensed vehicle weight.
 5. The system of claim 4 wherein: the flowdirector is operable to enable a hydraulic flow to at least one electrichydraulic cylinder having the higher weight-handling capacity inresponse to the vehicle weight being heavier and further operable toinhibit the hydraulic flow in response to the vehicle weight beinglighter.
 6. The system of claim 1 further comprising: A road platecoupled to the at least one electric hydraulic cylinder having thehigher weight-handling capacity and further coupled to the at least oneelectric hydraulic cylinder having the lower weight-handling capacity.7. The system of claim 5 further comprising: A road plate coupled to theat least one electric hydraulic cylinder having the higherweight-handling capacity and further coupled to the at least oneelectric hydraulic cylinder having the lower weight-handling capacity.8. A method for power generation comprising the acts of: providing aplurality of electric hydraulic cylinders; sensing a weight of anapproaching vehicle; in response to the sensing, determining whether thevehicle is heavy; in response to the determining, selecting at least oneselected electric hydraulic cylinder from the plurality of electrichydraulic cylinders according to whether the vehicle is heavy; inresponse to the selecting, directing a flow of a hydraulic fluid intothe at least one selected electric hydraulic cylinder; and using theweight to force hydraulic fluid out of at least one selected electrichydraulic cylinder.
 9. The method of claim 8 wherein: the hydraulicfluid forced out of the at least one selected electric hydrauliccylinder is collected in a pressurized accumulator and furthercomprising flowing the hydraulic fluid collected in the pressurizedaccumulator to a hydraulic motor.
 10. A power generation systemcomprising: a hydraulic fluid accumulator; and a two level road platecomprising: at least one electric hydraulic cylinder having a lowerweight-handling capacity and being coupled to the accumulator and atleast one electric hydraulic cylinder having a higher weight-handlingcapacity and being coupled to the accumulator; wherein the road plate isoperable to transfer a vehicle weight to the at least one lowerweight-handling capacity electric hydraulic cylinder in response to aloading of the vehicle weight onto the road plate and further whereinthe road plate is further operable to transfer the vehicle weight to theat least one higher electric weight-handling capacity hydraulic cylinderin response to the vehicle weight exceeding the lower weight-handlingcapacity.
 11. The system of claim 10 wherein: the at least one electrichydraulic cylinder having a lower weight-handling capacity is positionedover the at least one electric hydraulic cylinder having a higherweight-handling capacity.
 12. The system of claim 11 wherein: thevehicle weight is transferred through the at least one electrichydraulic cylinder having a lower weight-handling capacity to the atleast one electric hydraulic cylinder having a higher weight-handlingcapacity.
 13. A method for power generation comprising the acts of:providing a hydraulic fluid accumulator; providing a two level roadplate comprising: at least one electric hydraulic cylinder having alower weight-handling capacity and being coupled to the accumulator andat least one electric hydraulic cylinder having a higher weight-handlingcapacity and being coupled to the accumulator; wherein the road plate isoperable to transfer a vehicle weight to the at least one lowerweight-handling capacity electric hydraulic cylinder in response to aloading of the vehicle weight onto the road plate and further whereinthe road plate is further operable to transfer the vehicle weight to theat least one higher electric weight-handling capacity hydraulic cylinderin response to the vehicle weight exceeding the lower weight-handlingcapacity; and using a vehicle weight to compress the cylinders.